The present invention generally relates to removable storage devices for electronic information. More particular, the present invention relates to methods and apparatus for authentication data.
Consumer electronics including television sets, personal computers, and stereo or audio systems, have changed dramatically since their availability. Television was originally used as a stand alone unit in the early 1900's, but has now been integrated with audio equipment to provide video with high quality sound in stereo. For instance, a television set can have a high quality display coupled to an audio system with stereo or even "surround sound" or the like. This integration of television and audio equipment provides a user with a high quality video display for an action movie such as STARWARS.TM. with "life-like" sound from the high quality stereo or surround sound system. Accordingly, the clash between Luke Skywalker and Darth Vader can now be seen as well as heard in surround sound on your own home entertainment center. In the mid-1990's, computer-like functions became available on a conventional television set. Companies such as WebTV of California provide what is commonly termed as "Internet" access to a television set. The Internet is a world wide network of computers, which can now be accessed through a conventional television set at a user location. Numerous displays or "wet sites" exist on the Internet for viewing and even ordering goods and services at the convenience of home, where the act of indexing through websites is known as "surfing" the web. Accordingly, users of WebTV can surf the Internet or web using a home entertainment center.
As merely an example, FIG. 1 illustrates a conventional audio and video configuration, commonly termed a home entertainment system, which can have Internet access. FIG. 1 is generally a typical home entertainment system, which includes a video display 10 (e.g., television set), an audio output 20, an audio processor 30, a video display processor 40, and a plurality of audio or video data sources 50. Consumers have often been eager to store and play back pre-recorded audio (e.g., songs, music) or video using a home entertainment system. Most recently, consumers would like to also store and retrieve information, commonly termed computer data, downloaded from the Internet.
Music or audio have been traditionally recorded on many types of systems using different types of media to provide audio signals to home entertainment systems. For example, these audio systems include a reel to reel system 140, using magnetic recording tape, an eight track player 120, which uses eight track tapes, a phonograph 130, which uses LP vinyl records, and an audio cassette recorder 110, which relies upon audio cassettes. Optical storage media also have been recognized as providing convenient and high quality audio play-back of music, for example. Optical storage media exclusively for sound include a digital audio tape 90 and a compact disk 10. Unfortunately, these audio systems generally do not have enough memory or capacity to store both video and audio to store movies or the like. Tapes also have not generally been used to efficiently store and retrieve information from a personal computer since tapes are extremely slow and cumbersome.
Audio and video have been recorded together for movies using a video tape or video cassette recorder, which relies upon tapes stored on cassettes. Video cassettes can be found at the local Blockbuster.TM. store, which often have numerous different movies to be viewed and enjoyed by the user. Unfortunately, these tapes are often too slow and clumsy to store and easily retrieve computer information from a personal computer. Additional video and audio media include a laser disk 70 and a digital video disk 60, which also suffer from being read only, and cannot be easily used to record a video at the user site. Furthermore, standards for a digital video disk have not been established of the filing date of this patent application and do not seem to be readily establishable in the future.
From the above, it is desirable to have a storage media that can be used for all types of information such as audio, video, and digital data, which have features such as a high storage capacity, expandability, and quick access capabilities.
The present invention relates to storage media that utilizes magneto-resistive head (MR read/write head) technology. One benefit to MR head technology is the reduction in amount of data overhead by removing ID fields from data sectors on the disk. Magnetic disks without such ID fields are termed "headerless ID" magnetic disks.
Reading and writing with MR read/write heads to headerless ID magnetic disks within removable cartridges provide unique challenges not fully appreciated or contemplated by fixed disk drive units. For example, while removable cartridges are typically meant to be removed from a removable drive unit and transported to different locations. In contrast fixed disk drive units are typically not meant to be separated from a computer system and are relative stationary because of the relative bulkiness and heaviness of the fixed disk drives.
One parameter that is always different from removable cartridge to removable cartridge is the location of defects on the magnetic disk.
Defect maps are well known maps that maintain the address of locations on the magnetic disk that are faulty. For fixed disk drives, defect maps are often burned into a ROM, however for removable cartridges, defect maps are often resident upon the magnetic disk. Some defect maps are even compressed in order to save space on the magnetic disk. Because the defect map is stored on the magnetic disk, when the removable cartridge is inserted into a removable drive unit, the defect map is read from the magnetic disk and is used to determine the locations of bad sections on the disk.
One particular difficult problem that becomes more apparent due to the increased mobility of removable cartridges is that the data contained therein are more prone to unauthorized duplication or forgery. Thus what is needed is a method and apparatus for inhibiting duplication and forgery of removable cartridges, and a way to authenticate removable cartridges.